In a publicly known liquid sealed engine mount, an elastic movable diaphragm is provided in a partition means for partitioning a liquid chamber into a primary liquid chamber and a secondary liquid chamber to absorb an internal pressure of the primary liquid chamber. A relief valve is provided in an outer circumference of the elastic movable diaphragm in such a way that when the primary liquid chamber turns to such a negative pressure that the primary liquid chamber causes cavitation (this state shall be a condition of cavitation occurrence), the relief valve is opened to allow liquid of the secondary liquid chamber to be leaked rapidly to the primary liquid chamber, so that a liquid pressure of the primary liquid chamber is heightened thereby to prevent the cavitation.
As such an elastic partition member formed integral with the relief valve, there is disclosed, for example, the partition member which has a circular shape in a plan view and includes a thick-wall section of annular shape provided in an intermediate part in the radial direction thereof. An inner side of the thick-wall section functions as the elastic movable diaphragm, and the relief valve is integrally formed with an outer side of the thick-wall section. The thick-wall section is sandwiched by the rigid partition means from above and below so as to form an outer circumferential section of the movable diaphragm of the elastic partition member.